From owner-freebsd-questions@FreeBSD.ORG Wed Mar 16 09:54:05 2005 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1766116A4CE for ; Wed, 16 Mar 2005 09:54:05 +0000 (GMT) Received: from mailgw.dgrp.sk (mailgw.dgrp.sk [195.28.127.4]) by mx1.FreeBSD.org (Postfix) with ESMTP id 77D4643D1F for ; Wed, 16 Mar 2005 09:54:04 +0000 (GMT) (envelope-from lk@tempest.sk) Received: by mailgw.dgrp.sk (Postfix, from userid 1003) id A353D34A5A9; Wed, 16 Mar 2005 10:54:03 +0100 (CET) Received: from webmail.tempest.sk (unknown [195.28.100.38]) by mailgw.dgrp.sk (Postfix) with ESMTP id 8B82834A5A6; Wed, 16 Mar 2005 10:54:00 +0100 (CET) Received: from lk.tempest.sk ([195.28.109.47]) by webmail.tempest.sk (Lotus Domino Release 6.5.2) with ESMTP id 2005031610540050-433 ; Wed, 16 Mar 2005 10:54:00 +0100 Received: from lk.tempest.sk (localhost [127.0.0.1]) by lk.tempest.sk (8.13.1/8.12.9) with ESMTP id j2G9rj3g003361; Wed, 16 Mar 2005 10:53:45 +0100 (CET) (envelope-from koren@lk.tempest.sk) Received: (from koren@localhost) by lk.tempest.sk (8.13.1/8.13.1/Submit) id j2G9rjKR003358; Wed, 16 Mar 2005 10:53:45 +0100 (CET) (envelope-from koren) Date: Wed, 16 Mar 2005 10:53:45 +0100 (CET) Message-Id: <200503160953.j2G9rjKR003358@lk.tempest.sk> From: Ludo Koren To: xfb52@dial.pipex.com In-reply-to: <42370004.5060506@dial.pipex.com> (message from Alex Zbyslaw on Tue, 15 Mar 2005 15:32:20 +0000) References: <200503140938.j2E9c2EM024428@lk.tempest.sk> <42370004.5060506@dial.pipex.com> X-MIMETrack: Itemize by SMTP Server on Domino1/DGRP(Release 6.5.2|June 01, 2004) at 16.03.2005 10:54:00, Serialize by Router on Domino1/DGRP(Release 6.5.2|June 01, 2004) at 16.03.2005 10:54:00, Serialize complete at 16.03.2005 10:54:00 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on mailgw X-Spam-Level: X-Spam-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.0.2 cc: freebsd-questions@freebsd.org Subject: Re: Backup on DDS-4 tapes X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 16 Mar 2005 09:54:05 -0000 >> # /sbin/dump -Lu0 -B 41943040 -C 32 -f /dev/sa0 /usr >> >> >> > I would guess that your tape drive does hardware compression in > which case the amount of data which fits on a tape is variable. > In such a case you can't tell dump how big the tape is -- I > haven't used options like -B since 1600bpi reel-to-reel tapes, > except in my day you specified how many feet of tape you had > :-) > from man dump > -a ``auto-size''. Bypass all tape length considerations, > and enforce writing until an end-of-media indication is > returned. This fits best for most modern tape drives. Use of > this option is particularly recommended when appending to an > existing tape, or using a tape drive with hardware compression > (where you can never be sure about the compression ratio). It doesn't help either... The result is the same. > Don't know -L, must be a 5.x thing. Try: -L This option is to notify dump that it is dumping a live file sys- tem. To obtain a consistent dump image, dump takes a snapshot of the file system in the .snap directory in the root of the filesystem being dumped and then does a dump of the snapshot. The snapshot is removed when the dump is complete. If the .snap directory does not exist in the root of the filesystem being dumped, the dump will fail. This problem can be corrected by creating a .snap directory in the root of the filesystem to be dumped; its owner should be root, its group should be operator, and its mode should be 0770. > /sbin/dump -Lu0 -a -C 32 -f /dev/sa0 /usr > I use -b 64 as well. > Use cpio/tar at your peril as they may not do devices right and > may not understand filesystem flags. > --Alex lk